Advanced Programming in the UNIX® Environment

ptg10805159

696 Te rminal I/O Chapter 18

When we run the program from Figure18.14, we get the following output:

$./a.out

fd 0: tty

fd 1: tty

fd 2: tty

$./a.out </etc/passwd 2>/dev/null

fd 0: not a tty

fd 1: tty

fd 2: not a tty

Example —ttynameFunction

Thettynamefunction (Figure18.15) is longer, as wehave to search all the device

entries, looking for a match.

#include <sys/stat.h>

#include <dirent.h>

#include <limits.h>

#include <string.h>

#include <termios.h>

#include <unistd.h>

#include <stdlib.h>

struct devdir {

struct devdir *d_next;

char *d_name;

};

static struct devdir *head;

static struct devdir *tail;

static char pathname[_POSIX_PATH_MAX + 1];

static void

add(char *dirname)

{

struct devdir *ddp;

int len;

len = strlen(dirname);

/*

*Skip ., .., and /dev/fd.

*/

if ((dirname[len-1] == ’.’) && (dirname[len-2] == ’/’ ||

(dirname[len-2] == ’.’ && dirname[len-3] == ’/’)))

return;

if (strcmp(dirname, "/dev/fd") == 0)

return;

if ((ddp = malloc(sizeof(struct devdir))) == NULL)

return;